Elevator safety device



Oct. 8, 1935 4 LEE 2,016,332

ELEVATOR SAFETY DEVICE Filed April 29, 1933 Z INVENTOR ATTORNEY PatentedOct. 8, 1935 UNITED STATES PATENT OFFICE ELEVATOR SAFETY DEVICE ThomasLee, Westfield, N. J.

Application April 29, 1933, Serial No. 668,484

11 Claims.

This invention relates to safety devices for elevators, or hercable-operated apparatus.

An object of the invention is to provide an elevator of the cable typewith an improved automatic signal for warning the operator when theelevator is loaded to its safe capacity. Another object is to providesuch'an elevator with a similar signal for warning the operator when theelevator is overloaded. An elevator may be I equipped with either orboth of these signals, and the invention comprises novel features andcombinations of elements by which the stretch of the elevator hoistingcable operates the signals.

Still another object of the invention is to provide means for preventingthe starting of an overloaded elevator. Although the brake will usuallyholda heavily overloaded elevator before it is started, the brake isoften unable to stop the car again after it begins to descend. I

The invention can be conveniently and economically applied toconventional elevators of the cable type to signal the operator when theelevator is loaded to capacity or overloaded, and to prevent starting ofthe elevator when overloaded.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the accompanying drawing, forming a part hereof:

Fig. 1 is a diagrammatic view, partly in section, of an elevatorequipped with safety devices according to this invention.

Fig. 2 is an enlarged sectional view on the line 2-2 of Fig. l.

Fig. 3 is an enlarged plan view of the collar on the hoisting cable.

Fig. 4 is a diagrammatic view, on a reduced scale, showing a modifiedform of the invention.

An elevator H has a beam it to which is attached a hoist cable IS. Aceiling I! under the beam i3 has a door it for access to controlmechanism'above the elevator ceiling.

Signal lamps 2i and 22 are located in the elevator in position to beeasily visible to an operator standing by a conventional controller 24.

The hoist cable l5 passes over drums 28 and 21 at the top of theelevator shaft, and is connected toa counterweight 29. The drum 26 isrotated by a reversible electric motor 32. A brake 34 is applied by aspring 36 with suflicient force to prevent the motor 32 and drum 26 fromturning when the elevator is loaded and the motor circuit open. Asolenoid 38 in series with the motor releases the brake 34 wheneverpower is sup-,-

1 plied to the motor to drive it" in either direction.

scribed is illustrated diagrammatically in its simplest form for aclearer understanding of the invention, but it will be understood thatthe invention is not limited to elevators having only one cable, or toelevators having the simple direct motor drive shown in Fig. 1.

A bracket comprising a vertical sleeve 40 and base 4| secured to thebeam l3,'or to some other part of the-elevator, and a cylindricalsupport 42 fits into the sleeve 40. The support 42 is freely slidable inthe sleeve 40 but is prevented from rotating by pins 44 which are fixedto the support 42 and extend into vertical slots 46 in the sleeve 40.

The support 42 can be moved up and down, and can be held in any setposition by a screw 48, best shown in Fig. 2. The screw 48 threadsthrough the base 4i and has an unthreaded upper end which extends into arecess in the bottom of the support 42. The screw 48 is held in thisrecess by a pin 50, which extends into an annular groove 52 in thescrew.

The screw 48 passes through the web of the beam l3 and has a handle 54on its lower end. This handle is accessible from within the elevatorwhen the door I9 is open. By turning the handle 54 to the right or left,the support 42 can be raised or lowered in the sleeve 40. Electricswitch members carried by the support 42 are thus moved up or down withrespect to the elevator.

Five electric switch members GI, 62, 63, 84 and 65 are held betweeninsulating blocks 81 and 68 by screws 69 which pass through the electricswitch members, but are insulated therefrom by insulating bushingssurrounding the screws. These screws 69 thread into the top of thesupport 42. Insulating blocks are located between the electric switchmembers.

The electric switch vmembers are made of spring metal and are shaped sothat their ends are normally spaced from one another, except the ends ofthe switch members Bland 84 which are normally in contact.

A switch operating member comprising a split collar 12 is clamped to thehoist cable l5 by screws 14 (Fig. 3).

Referring again to Fig. l, the switch member Bl extends over the collar12 a short distance. above the collar when the elevator is not loaded.As the elevator is loaded, the cable i5 .stretches slightly and thecollar 12 moves up into contact with the switch member II and bends thisswitch member upward into contact with the switch member 62 when theload in the elevator is approximately equal to its safe carryingcapacity.

A lug ll, ilxed to the switch member 62, extends through an opening inthe switch member 63 without touching the latter. The upper end oi thelug it touches the underside of the switch member 84 or is very close toit when the switch members are in their normal positions. I

When the cable I! stretches enough to move the switch member l! intocontact with the switch member 82, the circuit through the signal lamp2i is closed and the lamp is lighted to indicate that the elevator isloaded to its safe capacity. Additional loading of the elevator causesthe cable I! to stretch further so that the collar 12 bends the switchmembers ti and 62 further and causes the lug II to move the switchmember 04 away irom the switch member ll and into contact with theswitch member I.

The switch members SI and N are in the motor circuit in series with thecontroller 24, and when these members are moved apart the motor circuitis open and the elevator can not be started. The

- member 84 touches the switch member ti.

The spacing of the switch member '5 above the switch member I4 is verysmall so that when the latter moves out of contact with the member 63 itimmediately moves into contact with the member 65, thus opening themotor circuit and lighting the overload signal lamp at substantially thesame time. There is a sheet of insulation I8 on the under side of theswitch member 83 so that no circuit is ever closed between the switchmembers I2 and OI.

The position oi the switch members Bi-BS is set by the handle 54 so thatwhen the elevator is stationary and is loaded to its safe capacity, or

any chosen load less than its safe capacity, the stretch of the cablecauses the collar 12 to move with respect to the elevator and. switchmembers a suillcient distance to move the switch member Bl into contactwith the switch member 82 and light the warning or capacity signal 2|.Moving the handle 54 in a direction to lower the switch members causesthe signal lamps to light when there is less load on the elevator. whenthe support 42 and switch members I l" are raised, a heavier load isrequired to stretch the cable ll sunlciently to cause the signal lampsto light. I! the cable it becomes permanently stretched after a periodof service, the handle 54 is operated to set the switch members "-8!higher and thus compensate for the permanent stretch of the cable.

The switch members I48 are located in posi-:-

tion to operate the signals at certain predetermined loads on theelevator when the latter is stationary. Acceleration of the elevatorwhen going up, and deceleration when going down, put an additional loadon the cable. Thus, the cable of a safely loaded moving elevator may bestretched further than that 0! an overloaded stationary elevator. It is,therefore, desirable to prevent the signals and motor cut-out fromoperating when the elevator is moving.

A relay II is connected in series with the motor ll. As soon as power issupplied to the motor to start the elevator. the relay Ii is energized,closes a normally open switch 82, and completes a shuntcircuit aroundthe switch members 83 and '4 so that the motor-circuit can not be openedby these switch members moving apart while power is being supplied tothe motor.

The signal lamps 2| and 22 are supplied with power through a switch 84which is closed when the controller 24 is in its neutral position but isopened whenever the controller is moved out 0!- neutral position.

The circuit for the motor 32 and the circuits for the signal lamps 2|,22 are separate, so that they can be operated on different voltage. Theswitch members Bl-GS and the controller 2i are shown connected directlyin the lamp and motor circuits,

but it will be understood that relay switches can be used to carry thelamp and/'01 motor currents if it is desir able to have only smallcurrents flowing in the switch members and controller.

' Fig. 4 shows a modified form or the invention, which diilers from theembodiment illustrated in Fig. 1 only in the structure for transmittingthe movement of the collar 12 to the switch members "-65. When theinvention is applied to elevators having a plurality of hoisting cables,the collar i2 is secured to one-oi the cables but the stretch of eachcable is relatively small. In Fig. 4 the collar 12 is placed higherabove the elevator and the length of cable between the collar andelevator is thereby increased.

A third-class lever II is pivotally connected to a bracket 90 on theelevator. A weight 82 at the free end of the lever 88 operates theswitch members in the same way that the collar 12 operates them inFig. 1. The collar is connected to the lever 88 by a cable 94, or othertension member. When the hoist cable I! stretches, the collar 12 movesupward with respect to the elevator and moves the lever 88 so that theweight 92 rises. The cable 94 and lever 88 are motion transmittingconnections through which the movement of the collar 12 is transmittedto the weight 82, which is the switch operating member in Fig. 4. Theseconnections multiply the the weight is further from the fulcrum oi thelever 88 than is the connection with the cable 54. Thus a small cablestretch can be made to cause a relatively large movement oi the switchoperating member.

The operation oi! the invention is as follows:

When the elevator is unloaded, or carries a load less than its safecapacity, the switch members I. and BI are in contact so that movementof the controller 24 completes the motor circuit, releases the brake 34,supplies power to the motor 34, and causes the elevator to go up ordown, depending on the direction of movement of the controller. Theswitch members ii, 62 and 85 controlling-the circuits of the signallamps 2| and 22 are in open circuit positions, and the signal lamps aretherefore not lighted.

As the load on the elevator increases until it is approximately equal tothe sale carrying capacity of the elevhtor, the cable ll stretches, andthe elongation of that portion of the cable be tween the collar I2 andthe cable connection'to the elevator causes the collar to move upwardand bend the switch member 6| into contact with the switch member 62.The controller 24 is in neutral position when the elevator is beingloaded, and thus a circuit is closed through the switch 84. signal lamp2i and switch members 8i and '2. The signal lamp 2| is lighted toindicate that the load on the elevator is approximately equal to itssafe capacity. The elevator can be started when the signal lamp 2i islighted and the lamp will go out as soon as the controller 24 is movedto start the elevator.

when the elevator is overloaded, the cable tween the switch members 64and 65 closes the circuit from the switch 84 through the overload signallamp 22, and with the controller 24 in neutral position the lamp 22 islighted to indicate that the elevator is overloaded and can not bestarted. Movement of the controller will extinguish the lamp 22 but willnot release the brake 34 or start the motor 32. Any suitable signals canbe substituted for the lamps 2| and 22. The invention can be applied toelevators or other hoisting apparatus in which the hoist cable isoperated by otherpower means instead of an electric motor. The preferredembodiments of the invention have been illustrated and described, butchanges and modifications may be made and various features of theinvention used with or without other features without departing from theinvention as defined in the claims.

I claim:

1. Hoisting apparatus including a hoisting cable, load carrying meanssupported by the cable, a signal for indicating that the load on thecable exceeds a given weight, and means operated by stretch of saidhoisting cable to cause display of the signal, said means including amember attached to the cable and movable with the cable in its directionof stretch, and a relatively fixed member.

2. The combination with a hoisting apparatus having a hoisting cable, ofa warning signal and an overload signal; means operated by the stretchof the hoisting cable, when the hoisting apparatus is loaded to its safecapacity, for operating the warning signal; and means operated by.further stretching of the cable for operating the overload signal.

3. Ina .cable hoist elevator, a signal for indicating that the elevatorload exceeds a given weight; signal operating mechanism includingmembers carried on the elevator; and means connected to the cable andmovable with respect to the elevator and said members as the cablestretches with increased ,load on the elevator, said means being movablein the direction of cable stretch and located in positionto cause thesignal to be operated when the cable is stretched an amountcorresponding to a predetermined load.

4. The combination with a cable hoist elevator, of an electric signal;switch means carried bythe elevator; switch operating means including amember connected to the hoisting cable some dis-' tance above theelevator and movable" with respect to the elevator and switch means asthe section of cable between said member and the elevator stretches withincrease of load; and

means for changing the location of the switch means to compensate forpermanent stretchot the cable or to set the switch means for operationat a different elevator load.

5. The combination with an elevator having a ceiling and a hoist cable,of a signal; signal oper-. ating means including members connected withthe elevator above the ceiling, and an element connected to the hoistcable some distance above the elevator and movable with respect to theele-,

vator and said members as the hoist cable stretches with increased load;and adjustment means above the ceiling and accessible to a person in theelevator, through an opening in the ceiling, for changing the locationof said mem- 5 bers to compensate for permanent stretch in the cable orto set the signal operating means to operate for a different elevatorload.

1 6. An elevator safety device comprising a signal; and mechanism foroperating the signal when the load on the elevator exceeds a givenweight, said operating mechanism including an element connected to thecable and movable with respect to the elevator when the cable stretcheswith.in-

creasing load; and motion multiplying lever onnections for t ansmittingthe movement of said element to other parts of the signal operatingmechanism.

'7. In combination with an elevator, a motor for operating the elevator,a controller for the ele- 2o vator; and means operated by stretch of asup porting cable of the elevator to prevent operation of the elevator.

8. The combination with an elevator having a hoist cable and drum; anelectric motor for rotating the drum; a brake for the drum and motor;electromagnetic means for releasing the brake; and a controller for theelevator for supplying power to the motor and the brake-release means;of a normally closed switch in the controller circuit, and meansincluding a member attached to the cable and movable with stretch of thehoisting cable, when the elevator is overloaded, to

open said switch so that the controller cannot supply power to the motorand brake release means.

9. In combination with an elevator, a hoist cable and drum, a motor forrotating the drum,

a brake for stopping the motor and drum, and r for holding them againstrotation; a controller 40 for the elevator for releasing, the brake andsup-- plying power to the motor; signal means operated by stretch of thehoist cable for indicating when the elevator is loaded to its safecapacity; and means operated by a further stretch of the hoist 5 cablefor rendering the controller inefiective.

10. The combination with an elevator having a hoist'cable and drum; anelectric motor for rotating the drum; a brake for the drum and motor;electromagnetic means for releasing the brake; and a controller for .theelevator for supplying. power to the motor and the brake-release means;of an electric signal and switch means controlling the operation of thesignal to indicate when the elevator is loaded to its safe capacity; anormally closed switch in the controller circuit and separate from theswitch means of said signal so that the signal circuit can be operatedwith a voltage different from that of the motor circuit; and meansoperated by stretch of the hoisting cable, when the elevator isoverloaded, to open said switch so that the controller cannot supplypower to the her to cause a display of the signal when the cable stretchreaches a given value.

THOMAS LEE. T5

